Texas county turns to spray-injection patching

Winters are known to be tough on roadways, but combine the harshest winter in 15 years with an extremely wet spring and the result is a lot of road maintenance in north Texas. These are the conditions that Greyson County, (an area located 60 miles north of Dallas) faced earlier this year. The county commissioner of Precinct 02, David Whitlock, went in search of the best method to fit the needs of his area. In addition to the weather variable, the roads in Precinct 02 were seeing an increase in traffic, mainly tractor-trailers that were taking a toll on roads that were originally gravel and then just rolled and chip-sealed. The roads were experiencing a great deal of alligator cracking leading to potholes as well as the shoulders being unable to withstanding the heavy loads and breaking away.

In Whitlock’s quest for a solution, he was informed of a method of repair called spray-injection patching and how this process would be a long-term solution for all his needs. He decided to set up demonstrations with various brands of spray-injection equipment, including the Crafco Magnum. The Magnum uses high-velocity air in conjunction with a screw auger to clean the repair area, apply a tack coat and then apply aggregate coated with asphalt emulsion, all in one continuous operation. The coated aggregate is also compacted during the application, leaving virtually no voids in the final repair which creates a long-lasting patch.

The county was impressed with how the initial repairs held up and chose to purchase a Magnum. They also located a 1997 model Magnum and have been using both units full time since July on the 350 lane-miles in the precinct. In comparing spray-injection patching to their previous method of repair, hot-mix asphalt, Whitlock has seen nothing but improvement in both repair quality and production.

“We could send two men and a truck over to the batch plant and they could wait around for a couple hours and still maybe not get any hot mix,” he said. One of the other benefits to the spray-injection repairs is the ability of the patch to adhere to dirt of the damaged shoulders, where the hot mix would not. The initial tack coat that is applied during the spray-injection process penetrates the dirt giving the patch a surface to stick to. The county also noted how well the high-velocity air cleans the repair area, including getting rid of any moisture in the area that can be troublesome to other repair methods.